1. Field of the Invention
The present invention relates to building construction supports, and more particularly to a cap enclosing an elevated base which supports a wood column or post, thus protecting the wood lowermost portion from rot and other deterioration due to exposure to moisture, heat, fungus and parasites.
2. Description of the Related Art
Wood has been a traditional material in the world's tropic and two temperate zones, especially where lumber is an indigenous product which is easily available locally. But in tropical regions such as Central and South America, Africa, and Southeast Asia, wooden structures are susceptible to deterioration from the effects of humidity, heat and ultraviolet radiation. Usually the lowermost portion (i.e., the base portion) of vertical wood columns which support a building is the most vulnerable structural element because it is most exposed to moisture. In buildings having side walls as in the temperate zones, water accumulates through seepage; in buildings on stilts as in the tropics, support column base portions are directly exposed repeatedly as rain water accumulates and evaporates. Therefore, the lifetime of a building depends largely upon how long its columns endure. Typically, the life of a wood column in the tropics is limited to about 20 years, with failure due to rot usually occurring where the column intersects the earth. But where rotting has been prevented, e.g., by placing a building on a solid foundation of stone, the building can last for hundreds of years.
There is an urgent need, especially in the tropics, for a method of building houses from lumber available locally which can produce houses which will last at least as long as those built using concrete. The problems in achieving such longevity are preventing the wood support column base portion from rotting, and providing a stanchion-type base to enclose and support the base portion which can withstand the high up-loads, down-loads and transverse loads to which the column would be subjected during hurricanes.
The elevated column base disclosed in U.S. Pat. No. 5,901,525, of which I am a coinventor and which is incorporated herein by reference in its entirety, provides a solution for both preventing rot and withstanding high loading. The column base includes a stanchion, a diaphragm and a cap, each monolithically molded from a thermoplastic. For regions and/or structures where high loading is not a concern, the principle taught therein of enclosing the lowermost portion of a wood column or post and its supporting elevated base to shield it from inimical environments can be applied in providing caps tailored to particular wood member and base combinations. An additional benefit provided by such enclosures is protection against impact from lawn mowers, weed whackers, and the like.
Elevated bases to raise wood columns and posts above concrete surfaces subject to wetting are widely used in the construction of buildings and ancillary structures such as decks, porches and fences. Many such bases are known in the construction arts including those disclosed in: U.S. Pat. No. 5,568,909 to R. J. Timko; U.S. Pat. No. 5,123,623 to J. F. McNamara; U.S. Pat. No. 4,995,206 to K. W. Colonias et al.; U.S. Pat. No. 4,958,470 to C. M. Han et al.; U.S. Pat. No. 4,924,648 to T. T. Gilb et al.; U.S. Pat. No. 4,644,713 to J. F. Lehman; U.S. Pat. No. 4,614,070 to K. Idland; and U.S. Pat. No. 4,199,908 to D. L. Teeters. However, none of these elevated bases include an assembly to shield the wood lowermost portion from the environment. Shielding devices have been devised, but in the context of protecting a wood member embedded into the ground. U.S. Pat. No. 5,090,165 to L. D. Kenny discloses a molded plastic sleeve which fits over the circumferential base of an embedded post or pole. The sleeve forms a barrier intended to retard the decaying or rotting of the wood. An umbrella-like rim at the top of the sleeve deflects excess moisture which may run down the member, and two vents extending from the sleeve base to several inches above the ground provide expansion areas for freezing should moisture accumulate in the sleeve. U.S. Pat. No. 4,972,642 to F. P. Strobl, Jr. provides a foot for supporting a wood post at the bottom of a hole which typically extends below the frost line. The plastic foot is monolithically molded and has a dishshaped bottom wall configured to be supported by the earth at the bottom of the hole.